Update Docusaurus version and deploy script

.github/workflows/pistache.io.yaml

@@ -7,16 +7,16 @@ on:
 
 jobs:
   pistacheio-deploy:
-    runs-on: ubuntu-20.04
+    runs-on: ubuntu-latest
 
     steps:
       - uses: actions/checkout@v2
 
       - name: Install dependencies
         run: |
-          sudo apt-get update && sudo apt-get install -qq npm --no-install-recommends --assume-yes
-          sudo npm install --global --silent yarn
-          sudo npm install --global --force --silent npx
+          sudo apt-get -qq update && sudo apt-get -qq install --assume-yes --no-install-recommends yarnpkg
+          sudo update-alternatives --install /usr/bin/yarn yarn /usr/bin/yarnpkg 10
+          sudo yarn global add --silent --no-progress --non-interactive npx
 
       - name: Build docs site
         run: |

pistache.io/package.json

@@ -12,8 +12,8 @@
     "clear": "docusaurus clear"
   },
   "dependencies": {
-    "@docusaurus/core": "2.0.0-alpha.70",
-    "@docusaurus/preset-classic": "2.0.0-alpha.70",
+    "@docusaurus/core": "2.0.0-alpha.75",
+    "@docusaurus/preset-classic": "2.0.0-alpha.75",
     "@mdx-js/react": "^1.6.21",
     "clsx": "^1.1.1",
     "react": "^16.8.4",